(While the latter five stores are making inroads, last year nearly nine in 10 apps were downloaded from Apple, according to Carolina Milanesi at Gartner.)

Revenue from apps is projected to be greater than $15.1 billion in 2011, up from $5.2 billion in 2010. The projections include the cost of the applications themselves and advertising revenue generated from within apps.

“We strongly believe there is a sizable opportunity for application stores in the future,” said Stephanie Baghdassarian, research director at Gartner, in a release. “However, applications will have to grow up and deliver a superior experience to the one that a Web-based app will be able to deliver.”

Between now and 2014, app revenues are expected to keep growing until they reach $58 billion — a 1,000 percent increase over 2010.

Despite the growth in revenues, 81 percent of downloaded apps will be free, according to Gartner.